I have some upcoming travel where I am planning to do some hiking/trail running. I am hoping someone could recommend to me an app that can use the GPS in my phone to help me navigate trails where there is no cell service. The easier (read: apps for dummies) to use, the better!
Thank you!
Iāve used this app out in Shindagin: https://store.avenza.com/
Most PDFs the DEC publish now will work with the app (called GeoPDF), and it works just like you ask: you donāt have service but the GPS will work with the map and show you where on the map you are.
Hereās more info on GeoPDFs: Georeferenced PDF Maps - NYS Dept. of Environmental Conservation
Iāve used āfootpathā and āalltrailsā. IMO neither one is great or awful. Most of the Challenge people seemed to have good luck with the RunGo app provided there was an actual route available.
Thanks!
I should mention that my travel will be out of state. Iāve checked RunGo, and the trail I want to do isnāt on there. All Trails might work. Iāll do more research.
Iāve used AllTrails and found it worked without cell service. Iāve also heard Gaia GPS is good.
This isnāt answering your question at all 
, but if youāre looking for known good runs while travelling, check out the Great Runs site.
Thank you for this link. This looks like a good website, already found a couple of runs to try!
Do you know how accurate āon the goā is for elevation and distance?
As far as Iāve been able to tell, OnTheGoMap has fine data for distance and elevation when mapping roadsāit relies on OpenStreetMap data. A little less so with trails because the trails that OnTheGoMap knows about donāt always match what I know to be true in the real world, so distance accuracy will suffer then. The same is true if you have to guess at where a trail is. Elevation accuracy is likely to be good at all times because the mapping data should be decent everywhere. The main issue there is bridges, which throw things off weirdly.
I really like OnTheGoMap, and had thought to use it as the basis for the Two Hollows Monster Marathon and Half website, but found that it measured the course a half-mile short of 13.1 miles compared to GPS measurements made by several runs encompassing various runners and various watches, all of which agreed quite closely with one another. So you can probably consider OnTheGoMapās distances in the right ballpark but somewhat approximate.
The comparison between GPS watches and online maps is a tricky one. We tend to take for granted that GPS watches are accurate since theyāre what we use every day. And to some extent, theyāre truth for usāit doesnāt really matter whether or not theyāre precisely accurate because thatās what we think weāre running. And a half mile here or there isnāt important.
However, when I was creating the RunGo directions for the Lick Brook & Treman FLT course for the FLRC Challenge last year, I was starting from @Petoriusās GPS track from running it, which was a bit longer than the believed 13.1 miles. What I found upon zooming all the way in was that his track readings bounced back and forth across the trail constantly, forcing me to smooth point after point to ensure they were all on the trail that appeared on the map. (Iām not sure what RunGoās base map is, or where it got the trail markings, but they generally matched up with what was on the ground.) By the time I had finished smoothing the entire course to the marked trail, it was back to that 13.1 miles Iād initially estimated from OnTheGoMap. Various other GPSes also got different numbers: for instance:
In other words, my sense is that we can trust OnTheGoMapās algorithm to do the right thing and come up with an accurate distance. The question is if the lines itās putting down to track roads and trails match up with what runners will do in reality. Similarly, GPSes tend to fall down when following the exact trail too, due to reception problems from trees and terrain, coupled with tight turns where the GPS may not catch up with you instantly.
Of course, it doesnāt matter much for trails. Even in a race, no one really cares about the precise distance because the terrain and conditions affect times so significantly, and thereās no comparison against other trail races of the same distance. In road or cross-country races, when the goal is to have a course of a specific distance, the only real solution is to wheel the course.
And for training, whatever. Just go with what the GPS watch saysāitās good enough. 
Iāve read through this thread and thought Iād add some notes on GPS watches and trail running, based on my experience with various watches and phones over the years.
Plotting a route using an app like RunGo is probably a lot more accurate that what you record on a GPS, assuming you smooth out the route to match the trail as it appears in the map. Like Adam said, distance is measured inaccurately because it doesnāt account for tight turns, and sometimes the GPS signal is hindered by clouds or tree cover. GPS does not record data points continuously. Instead, it records your location over a series of intervals (i.e. every 1 second or every 5 seconds) and then makes educated guesses to fill in the gaps. The higher the frequency of the recording, the more accurate the distance and pace will be, but this drains the battery quicker and fills up the deviceās internal memory sooner, as it is recording a larger data file.
In general, dedicated GPS devices, such as a running watch, record more accurately than phones. This is because the GPS is the watchās main function so the manufactures use the best technology possible for a given retail price point. On a smart phone the GPS is one of hundreds of features so the manufacturers are less concerned with high level GPS accuracy. The difference in accuracy is less of a factor running in roads or an outdoor track because there are fewer turns and less tree cover to weaken the GPS signal.
Re my GPS track for the Lick Brook Challenge course: my Suunto 9 GPS watch measured a lot more accurately during the first year I owned it. A software update in 2020 somehow caused it to consistently measure about 5% long on trails. Based on mapping software and prior runs on those trails with my older watch, I think the actual distance is around 13.3-13.5 miles. Nancyās new Monster course is also very close to 13.1, despite measuring 14 when I ran it a month ago.
Lastly, if youāre interested (as I am) in using a watch to track vertical gain on your runs, a barometer is much more accurate than an altimeter, but it also adds to the retail price.
Any questions, let me know and Iāll answer best I can!
@SarahG Avenza and Gaia both work well if youāll be running someplace without a reliable cell signal. Both apps allow you to load a .pdf of a trail map into the app, then display it with an overlay while the phoneās GPS shows your lactation in the map. Itās best to practice and get familiar with the features before using it in the woods so you donāt risk getting lost. Also, if youāre relying on the app and map for navigation, itās best to use your phone in airplane mode so you donāt risk draining the battery and getting lost with no map (which Iāve done before!)
Gaia or AllTrails! 